Pulverizing apparatus



o. A. KREUTZBERG PULVERIZING APPARATUS Filed March 17, 1921 2 sheets-sheet 1 Jan. 20. 1925.

o. A. KREUTZBERG PULVERIZING APPARATUS Filed March 17,

1921 2 sheets-sheet' 2 WW2-Z570. O ZOA /ffeaz wy Patented J an.- 20, 1925.

UNITED STATES l V1,523,881 PATENT OFFICE.

OTTO A. KREUTZBERG, OF LAKE lBLUFF'. ILLINOIS,l ASSIGNOR TO BLANTO'N-KREUTZ- BERGCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF'ILLINOIS.

PULVERIZING APPARATUS.

Application lcd March 17, 1921. Serial No. 452,986.-

To all whom t may concern.'

Be it khown that I, OTTO A. Knnu'rznnno, a citizen ofthe United States, residing at Lake Bluff, in the'county of Lake and State of Illinois, have invented certain new and useful Improvements in Pulverizing Apparatus, of which the following is a specification, reference being had to the accompanying drawings, forming a part thereof. p

The purpose of this invention is to provide ali improved construction for pulverizing hard material adapted inone of its forms for separating thematerial according to iineness, so that only that which is pulverized to a desired degree shall be delivered, the remainder being returned for further treatment. It consists in the elements and features of construction shown and de- I scribed. as indicated in the claims.

In the drawings:

Figure l is a vertical axial section of .a structure embodying this invention.

. Figure 2 is aldetail elevation of a portion of the structure shown in Figure l, a portion of the casing being broken away, said shaft and bearings lshown in section.

Figure 3 is a detail section at the line, 3 3. on Figure 1.' v

Figure l is a section at the line.l44, on Figure 3.

Figure 5 is a detailed section at the line,

on FigureQ.

Figure 6 is an axial section of one of the two rolls which alternate around the table with those shown in Figure l, showing the differing order of assemblage of the roll sections on the axle.

Figure 7 is a section at the line, 7 7, on Figure 1.

The structure shown in the ydrawings comprises a support,`1, upon which there is mounted for rotation about a vertical axis a table` 2. having its upper face dished for lodgment thereon of pulverizing rolls, 3, which are mounted for rotation upon axis, 4..,hinged upon brackets, 5. mounted upon the support. the position ofthe hinge and the form of the rolls being adapted to the slope of the dished table so. that the rolls lodge along their entire length upon the table and are rotated about their own axes .as the table revolves about its axis by friction al engagement of the rolls with the table and with the material thereon.

While, in the' main, thev pressure for pulverizing is derived by gravity from the weight of the rolls.,it is desirable to provide additional means which may be modified to vary the pressure according to the character ofthe material, and for this purpose each of the roller axles, 4, is terminated by a T-titting, 4a, which may be considered in genera-l as a part of the axle. the cross of the T heilig fitted between the lugs, 5a, of the bearing bracket,v5, while from the cross of the T there is extended a second lever arm, 4l. approximately at right angles to the roller sh aft, 4t. Upon the bracket, 5, there is formed at thelower part in. the angle between the vertical and horizontal flanges of the web of the bracket, a boss, 5, whose vtablet faces the downwardly-projecting end of the lever arm, 4; and between said boss and said lever arm there is interposed a spring. 19, at whose outer end there is lodged a block," 19a;and through the end of thel lever arm, 4b, there is set a tension screw, 2i, which operates in the head of the block, 19a. and is provided with a jam nut, 21a, to secure it as set in the'lever arm, 4", for adjusting the tension of the spring to vary .the pressure `of the roller.

The material to be treated is designed to be delivered to a conduit comprising a. terminal duct, 6, which delivers it at the center of the table lover an upraised central portion or tablet, 7, thereof. by which it is initially spread outward, the upraise being sloping at its margin so as to lodge the material upon the table proper at a little distance from the center of the table, whereby the centrifugal tendency resulting from the rotation of the table, operates to move it further outward and enter it between and under the rolls as the latter roll upon the table. Preferably the form of the uprase, 7, is 'as shown, comprising a eentral flat tablet portiorn, and marginal sloping portions, 7b, and the diameter of said flat tablet portion is greater than the diameterof the discharge mouth of the conyduit pipe, 6, by an amount such that the angle of slope of the cone frustrum whose larger base has the diameter of said ilat portion and whose smaller base hasv the diamter of the mouth of the pipe, 6, and whose height is the distance to which the mouth of the pipe, 6, will be raised above the flat portion for maximum discharge of material,

shall be substantially the angle of repose of 'form of the upraise,

slope of table revolves,

the material. The purpose A'of this 'specic 7, is that thereby when the rotation'of thetable is arrested, the material which is being delivered through .the pipe, 6, automatically'becomes a means of closure of the delivery aperture between tne end of the pipe, 6, .and the tablet, the material which is being delivered, not being carried away by thecentrifugal force, accumulating'in a pipe upon the ilat tablet which will not decrease nor flow away, because ofthe angle of its slope beinga's indicated, the angle of repose of the material.

The centrifugal action of the 'material retarded by gravity bythe up'wardvoutward the table when this is tapered, causes the material to 'advance outwardly along the table under the rolls slowly as the path, and being repeatedly crushed and ground by the rolls, until'it-emerges at the circumference of the table, ground or pulj izin verized to the degree of ineness desired. The ra'te of its advance outward from the centerof the table tothe lcircumference and' thereby' the rate of exposure to the pulveraction of the rolls on the table may be regu ated'by the speed of rotation of the table, said speed being adapted to the char; acter 'of material, so that it within the operation of the device long enough according to experience, to reduce the most refractory parts to the desired degree -of ineness by the time it is' advanced tothe circumference of the table.'

The support, 1, is apertured at an annular area situated under the outer circumference of the table, as seen at 1, so that the material delivered over the outer margin ofthe table, through ,the Vannular throatway, 1", formed between the margin of the table and a throttling member, 1h, mounted on the cas;

ing, 12, passes through said apertures, 1a*- and from the lower-'side of the support the D is suspended a `funnel or, gathering casing, 14, encompassing the annular apertured area of the support, so that the material delivered'through said apertures is received by the casingand gathered for-discharge at its discharge mouth, 14'. A c lindrical casing member, 12, encloses the table and tlherolls above theA support and outside the circle of" the apertures, 1", said casing being notched at its upper edge at 12, to accommodate the axles of the rolls, permitting the rolls to -be swung out of the casing for attention or for clearing the table. From the top of the cylindrical casing member, 12, the enclosure is continued upward for discharge of the pulveriz'ed material when provision is made for separation by air current, as is one mode o'f .use of the structure, as hereinafter more particularly explained; said extendedcasl mg consisting of interlocking sectors, 12",

l one sector for each rollv constituting aconfollowing in fact a spiralv will bekept' ing pipe terminal,

. se arated or ythe diameter of tie casing member, 12, the

casing being thence continued upward in the cylindrical portion, 12Z, which is provided with. a central discharge hereinafter dlescribed. Suspended, centrally within the funnel portion, 12y byr means of bracket arms, 22, extended from the part, 12', is

the receiving funnel proper, 17, into which the material to be treated is conducted by a feed pipe, 17, which 'leads in through the cylindrical upper member, 122, as seen in Figure 1. The lower end, 17, is connected for discharge with the two-part telescoping` delivery tube comprisin the parts, 1,8 and 6, the former carried fixe ly on the lower end ,of the funnel, 17, and the latter telescoping outside of said former tube, 18 (whereby its discharge mouth is lmade adjustable, as above indicated, with respect .to the central tablet, 7, of the upraise member, 7. And

for this adjustment, Said telescoping member, 6, has two pairs of links, one pair at each side of saidl member, 6 pivoted thereto upon the same pivot, 19", the two links of each.v pair diverging from their said pivot upwardly, and being connected to nuts, 19, mounted for travel in and out on a screw shaft, 20, said shaft having for said nuts, respectively, as shown at 20, 20". Said shaftis journaled in a litting, 21, which serves to connect the telescoping pipe members with the funnel, 17 the nuts being on the shaft outsideof its journal bearings shown at 20, and the shaft extending out through the vouter funnel member, 12V, of the casing for operation from the exterior for adjusting the telescop- 6, `as described.

22 1s a square rod which is'steadied at its upper end in a bearing;r on the shaft, 20, and at the lower end is mounted to rotate with the shaft, 2. Its function is to cause the breaking up of any. exceptionally large fragments fedv into the delivery tube and to prevent bridging of the material in the tube by agitating it'and breaking up the larger pieces by the encounter and engagement between the corners of said rod, 22, and the tube Wall.

When the pulverized material is not to lbe graded but is to be kept onklthe ta le until Cpulverized to a desired degree-,of

then delivered over the margin right-hand and left-hand threads ou I' throughthe throatway, 1", and

means of a discharge-controlling ring, .25,

cylindrical in form, having its wer im roverhanging the outer margin of the tablev and adapted to be adjusted vertically to produce a crevice of any desired width between its lower edge and said table margin, so that any material which reaches the margin of the table, having passed the rolls too large to pass the crevice, will be stopped by the ring and thereby thrown back between theV rolls to be further operated upon by them until crushed to tlie desired degree of neness. And to ensure such return. of the insufiiciently reduced fragments there is de- -controlling ring, it is carried by a plural-ity ot stems, 25, prei'ierablyv one for each be-l tween the rolls, said stems projecting out through the casing' member, l2, which is slotted vertically for that purpose, and outside the casing said stems are engaged in eye-bolts, 2G, which in turn are engaged in brackets, '27, secured upon the outsidel of said casing member, 12, nuts, 26a, 26, on said` eye-bolts above and below the engagement of.stems of said bolts with said brackets, serving to adjust and secure at adjusted position said discharge-controlling rin 25 -As shown, said discharge con troiling ring consists of a lower and upper part, the lower part being heavier and thicker as is necessary .for insuring its fixedness of form, and affording anchorage for the supporting stems mentioned, the upper partbemg of thin material serving to extend the ring .up past the height of the rolls, and being notched to accommodate the roll shafts for their swinging in and out as above described, and for their slight rise and fall in the operation of crushing material on the table. The upper part, 25h, serves and is required for arresting and returning to the table flying fragments of the material undergoing pulverizing.

.The means of rotating the table consists of a gear, 8, mounted upon the stem or spindle, 2, of thel table, said gear being driven `by a pinion, 8, mounted upon a driving shaft, 9. The. entire driving train is enclosed in a housing` 10, suspended from the lower side of the support, 1, having a step bearing, 10a, at the lower end for the spindle table shaft, 2a. The housing, 10, constitutes a grease chamber for containing lubricant for the gears: and any suitable provision is made for conducting lnbricant to the'several bearings. Said hous` ing, it will be observed, is suspended withinV the funnel or gathering casing, 14:, which constitutes an annular chamber around the housing` the latter serving to prevent eon` the pulveri-,Zed material getting into the gears or bearings.

AS above indicated, a very desirable mode of useof this structure consistsI in causing' a current of airto passthrough it from below the table up aroundl the circumference thereof1 thereby traversing the film of ma ierial delivered over the circumference of the tablet, such air current being graduated as to its velocity .so as topick up the material thus delivered and carry it up above the rolls to a point where the air velocity is less, where portions of material which are too coarse, to be held suspended by the air current of the first mentioned velocity selected, will be dropped and will fall again between the rolls onto the tablet for .further crushing and grinding, while the finer portions 'which' can be lifted by the air current of a given'velocity are car ried with said air current out through the casing members to the point of accumulation and storage. Thel path of the material thus lifted is through the annular throat between the frusto-conical casing member or funnel, 12V, and 4the funnel, 17@ The material, however, does not escape by passing directly upward from the said annular ,discharge from between the two funnels.

On the contrary, the cylindrical n'ien'iber, 12p, is closed at the top over an outer circumferential portion, the suction or exhaust connection being made at the center of the top web, 12m, of said upper cylindrical poi'- tion, 122, as seen at 13; and there is projecting downward from said web within the said cylindrical casing member, 12p, a cy `lindrical flange, 12, whose diameter is substantially twice that of the exhaust connection, 13: and telescoping outside of said iange l2, is an extension member, 12p, which may be adjusted on said flange, l2, by means of an operating arm or stem, 12", extended upward through the top web. 12m, and accessible exteriorly for such adjustment of theextension. 12p. The intention of this adjustable extension in connectionwith the entire construction of which it 1s a part,

is to enable the operator to vary the an nular air gap between the lower end of said extension, 12", and the funnel. 17, be low it to cause the velocity of the air to be varied according to the degree of ineness to which it is desired to reduce the material before permitting it to leave the apparatus. For it will be understood that as the air current passing up through the annular opening between the upper margin of the funnel, 17, and the frusto-conical case membei'. 12%', is reversed and deflected in the annular space loutside/of the nange. l2, and the extension, 12p.' in the cylindrical case member, 12z` and returns down around the lower end of the extension. 12p, the larger and coarser material will be thrown out tangentially'to the current as it is reversed around the lower margin of the part, 12D, and enters upwardly into said pipe, Said coarserl material being thrown down' into the funnel, 417, -and causedl to pass again over the table under the vrolls for further crushing.` And also, any material too coarsev to vbe carried by a current having thevelocity which is controlled by the area of the annular opening between the lower end ofthe part, 12p, and the funnel, 17, but which is not thrown out tangentially .as stated, in thc reversal ot the direction of the air current as it turns upward, will be 1g moving upward through the parts, 12D and 12"to the iinal outlet at 13, and falling into theV funnel, will be carried again over the table for'further reduction.

It will be understood upon consideration of thedrawing, that the maximum air velocity would be experienced at the margin of the table, the totalarea of the throatway lafforded atl", being less than the cross-section of the air current -at any other part of the path, and that consequently much material will be lifted at that point which will be subsequently dropped after the air cur rent has been deflected inward over the rolls and before it has passed out between the two lfunnels, 17 and 125'; and that there may be repeated returns before thenal emergence of the material reduced to the desired degree of ineness. The vertical adjustability of the throttle member, 1b, provides for varying the cross section and maximum velocity 'of the air current atthe margin of the table and thus varying the ineness of the material carried upwards by the air blast at. this point. Such variation of lcross section 'results in the downward adjustment of the throttle member, l", away from thebevel of' the under edge of the table as seen at 2x, and in Athe upward adjustment of the throttle throttle itself, as seen at 1y. justability of the throttle mounting it by several stems shown in Figure 1 at lz,

The vertical adis `obtained ,by

extending through shown at 12",l in Figure, nuts, 12, being applied on the stem outside the casing4 to clamp them in adjusted position. "Certain details of construction shown in the drawings require description.

`It is desirable that each roll should be lmade of a plurality of narrow 4sections so as f to take` from the table rolling speed independently of each other, each according to 0 the circumferential'speed of the zone of the 'j/ftable. on which itl rests and rolls. `And in order that this division of the rollsinto sections as seen in Figure 1 may not leave untraversed zones on the table between the zones traversed by the separate sectionsv 0I dropped by the air current while the current` nember away from .the under bevel of the of which one 1s l vertical slots in the casing of which one is b the rolls, said sections, 3*, are made as seen in Figure 1, with their table-engagin periphery, 3', offset from the middle o the width of the roll section, leaving a hub, 3, projecting at one end and a central recess, V3", of somewhat greater diameter than the hub at the other end, the `hub of one section being entered in the recess of the other section when the two sections are assembled on the shaft. Byv reversin the position of the sections in alternate rol s, the tracks of the sections of each roll constitute zones on the table covering the interval between and the margin at the inner or outer side beyond .the zolres which constitute the tracks of the next ro he particular construction shown, to-wit: thei roll sectionshaving each at one end a hubV and at the other end a recess adapted to receive the hub; results primarily from the means Vadopted for protectin theV journal bearings of thel rolls on the ax es from dust arising from the material to be treated. For this purpose the end of the axle has a cap nut, 3", secured onto it, closing that end of the journal bearing, and this may be further protected" by a dust cap, 3', as seen in-Figures 1 and 6. At the other end of the other roll section the protection is aorded by recessing theroll as seen at 3", and providin the sleeve, 3, which constitutes the hin p end portion of the axle, with aflange,v 3', whose periphery has a'groove to receive a packing, 3', which seats on the inner peripheral wall of the recess 3. The roll sections are extended in the hub 3, at the end opposite 'that which has the recess, 3', and the periphery of the hub has a roove, 3", to re ceive a packing, 3', adap to seat on the inner peripheryof the recess, 3. In Figures 1 and 6, the different modes of co-operation of the recesses and hubs, flanges and packing for lexcluding dust, is shown in the reverse order of assembling of the two roll sections for the purpose abovestated of causing the overlapping of their tracks as they roll upon the table. y

To provide for swinging the rolls out of the casing for any purpose for which it may enecessary, the member, 12', of the casing has ,sliding doors, 12", for which retaining and guide bars, 12g, and 12", are provided on the outside of said casing member around the apertures made for the exit of the rolls, said doors having operating handles, 12", and the neck port-ion, 121, of separately removable sectors which are latched in place by latches, 12', on the lower end of the sliding doors,r12. To close the notches, 12", in which the shafts of the rolls swing, there are provided two-palrt slides, 31, 32, (see Fig. 2) for which` slideways are provided at-the lateral margins of said notches l as seen at 33, ese slides obviously must be adapted to rise and fall with the roll of the casing made.

lao

shaft, as the rolls are lifted' and fall in the passage of material under them as the table rotates; and for this purpose the two parts, 31, 32, are connected by rods, 35, extending on opposite sides of the roll shaft, and through lugs, 36, on the upper part, 3l; and above the lugs wing nuts, 37, are provided for securing them. When a roll is to be swung out of the casing for attention, the wing nuts will be removed and the upper part, 31, of the slide will be withdrawn from the rod, 35.

Material to be pulverize/l is fed centrally of the table on which it migrates outwardly to be crushed by the rolls. This outward movement is due to centrifugal force; and, to prevent too rapid outward movement of the material, the table is provided with-an annular track which is inclined downwardly at a slight angle from its periphery toward itscenter.

Inevolving the present type o-f pulverizer, I found that good pulverizing, with a machine of the present type, involves the proper coordination of two factors, namely, (l) rotational speed of the table, and, (2) the angle of inclination of the table.

As a result of experimentation, I have found that the 'best crushing action takes place when a roller has a relative speed of from 700 to 1000 feet per minute with re.- spect to a table. In other words, the relative speed of a roller and a table should be suflicicntly high so that there is enough energy of impact of a roller to obtain good crushing action. If a roller passes slowly over a particle to be crushed, the only force tending to produce crushing is that due to the weight of the roller; on the other hand, if the roller moves with a sufficient degree of speed, it will be obvious that the kinetic energy or impact on a particle will be considerable. Another' factor which assists in the pulverizing action is that the rollers have a differential speed relation with respect to a table producing a grinding or attrition action with respect thereto.

With atable approximately four feet in diameter, it is necessary to drive it at about 7 0 R. P. M. in order to obtain a. peripheral linear speed around 800 feet per minute. This speed being desirable fromlthe standpoint of thebestcrushing impact, it was necessary to dish the tablel slightly in order that centrifugal force might besufliciently opposed by gravity to impede the outward movement of material so that it might be properly crushed. I have found, under the circumstances just stated, that an angle ofapproximately 12 is sufficient for this purpose. Best grinding takes place when there is neither a clogging of the table with material due to insuicient outward lmovement.

.nor too rapid .outward movementl which would result in too small a percentage of ward movement of a particle to such an extent that cach particle describes a spiral path and is passed over a number of tlmes before discharge from the table.

'nsv

while i have mentioned roo to 1000- feet 'i per minute, depending on the character of material, the'harder the material the higher the speed, as being a desirable speed for best f Aimpact or crushing operation, it is to be understood that by this I mean a minimum speed, at which the best crushing action takes place. Of co-urse, greater impart or vkinetic energy would be available at higher speeds; however, at such .high speeds centrifugal force acting on the' material would become greater and the power required to operate the machine would be increased. at a much greater rate with little, if any, increase in capacity. By a speed of 700 to 1000 feet per minute, I mean the-best practicable speed at which crushing of materials may be most 'efficiently accomplished.

l. A vpulverizing apparatus comprising a rotating table and pulverizing rollers mounted for rolling thereabove by frictional engagement therewith or with the material thereon, the table having. the. surface on which the rollers are lodged sloping downward from its circumference toward its center at an angle not exceeding fifteen degrees with respect to the plane of rotation, whereby movement of the material across the table due to centrifugal action is sufficiently retarded to produce maximum crushing, means for mounting the rollers for movement toward and from the table, and means for adjustably loading the rollers whereby al crushing pressure in addition to that due to the.weight of the rollers may be had.

2. A pulverizing apparatusgcomprising a rotating table and pulverizing rollers mounted for rolling thereabove by frictional engagement therewith or with the material thereon, the table havilng the surface on which the-.rollers are lodged sloping downward from its circumference toward its center at an angle not exceeding fifteen degrecs with respect to the plane of rotation, whereby movement of the material across the table due to centrifugal action is Suthciently retarded to produce maximum crushing,l non-rotating axles on which the Lrollers are mounted for rotation, the axles being pivoted 'at the outer ends for swinging in vertical planes to carry therollers toward and from the table, and adjustable means for biasing theI axles so 'as to exert pressure of the rollers on the table, whereby' a crushing pressure in `addition to that due 4to the weight of the rollers may be had.

3. A pulverizer comprising in combination with a fixed support, a rotating table having. an annular track-which is .inclined y downward' from its periphery` ttothe entire weight cf .the rollers is effect-ive I to assist in crushing material onzthe table,

means for adjustably loading the rollers,

whereby the bearing pressures thereof-on` the inclined annular ,track may be varied, y

Sdown to carry its height through the horiy"zontal plane ofathe delivery edge of the means ford'eliveri'n material to be treated at the inner ends o the rollers, and means for receiving'the pulverized material from the outer edge of the table.

4. In a pulverizing apparatus, the combination of a fixed support, a rotating table having a disli'ed upper surface, means for delivering material to be treated onto the table,.means for pulverizing the material on means and-having its lower edge'overhangas" the table,vth e material having free course over: the table toward the circumference, whereby'the rotation ofthe table tends to discharge the pulverized 'material centrif ugallyja'gainst gravity due to the dished form of the. tab e surface, a discharge-controlling .ring encompassing the pulverizing ing the circumferentialmargin ofthe table, and means forfadjusting said ring vtoward and from the table to` vary the discharge between its lower edge and the e.; 5..In a ulverizing apparatus, t-he come binaticno a'ixedsupporting structure, a

rotating tablehavin'g a dished upper surface, means for delivering material' to be treated onto the table, means for pulverizing materialen the table, a guard ring encompassing the pulverizing means and ex'- tendlng upwardlyfrom a point above the outer margin'of the table substantially to the level of the top of the pulverizing means for arresting flying fragments of material coming from the table and return- Iing such fragments tothe table, and meansy for supporting yring upon 4the fixed structure.

6, A pulverizing apparatus comprising in combinationwith -a fixed supporting structuie a rotatingtable having a dished upper surface, and pulverizin rollers mounted dished surface by frictional engagement therewithl crwith the material thereon; means for delivering the' .material to be treated onto the table at .the

innerends Jof the rollers and `for permitting its delivery off the table at the outer circumference of the latter, a. casing which en- .7. The construction defined in claim .4 A

foregoing,the throttling device being a frusto-conicatlJ annulus mounted for vertical .adjustment on the casing, its inner or lesser diameter being at its upper end and a proximating the diameter of the table' e ,.means for mountitrigi and adjusting said annulus'being adap for moving 1t up and upperv surface of the table.

8. A pulverizing apparatus' comprising, in :combination a' fixed supportin structure, a rotating table having a dish uppersurface, 'and rollers for ulverizing material supplied? yto the tab e, a tube through which thev material is fed onto the table at the inner ends of the rollers and means permitting its delivery of' thetable at the outer circumference thereof, the table havin onof material delivered-through the tube a central upraise onto ywhich the materlal is delivered, said upraise having n iiat'top-to a diameter in excess of the'diamf eter ofthe feed tube, for lodgement therein a pile sloping 'at the angle'of repose of the materiah said uprai'se dropping off abruptly from said flat top to a slope at approximately the angle o the repose.

9. A pulverizin'g apparatus comprising, in .combination witha fixed support a `rotating table, andpulverizi ranged above the table for pu verizing materidl supplied to the latten-a casin encompassingthe pulverizin 'means an extending thereabove, a' fe hopper ositioned above the pulverizing meansat t e central part of the table, a feed tubeextending from 'the delivery of the hopper downward and overhanging the table at the center thereof, said tube comprising two telescopin'g members, a horizontal shaft having right-and-left-threaded portions journaled' on the hopper,l threaded sleeves on the said-threaded portions respectively, and links fromsaid sleeves to the lower and outer telescoping member of the tube, said shaft being extended out through the casing for exterior `ac'cess to rotate it to raise and lower saidlower telescopin member.

In testimony whereof, I have ereunto set my hand at Chicago, this 7th day of F ebruorro A. KREUTZBERG.

roo` 

